Field measurements for calibration of simplified models of the stiffening effect of infill masonry walls in high-rise RC framed and shear-wall buildings

As a type of nonstructural component, infill walls play a significant role in the seismic behavior of high-rise buildings. However, the stiffness of the infill wall is generally either ignored or considered by simplified empirical criteria that lead to a period shortening. The difference can be greatly decreased by using a structural identification methodology. In this study, an ambient vibration test was performed on four on-site reinforced concrete high-rise buildings, and the design results were compared with the PKPM models using corresponding finite element(FE) models. A diagonal strut model was used to simulate the behavior of the infill wall, and the identified modal parameters measured from the on-site test were employed to calibrate the parameters of the diagonal strut in the FE models. The SAP2000 models with calibrated elastic modulus were used to evaluate the seismic response in the elastic state. Based on the load-displacement relationship of the infill wall, nonlinear dynamic analysis models were built in PERFORM-3 D and calibrated using the measured modal periods. The analysis results revealed that the structural performance under small/large earthquake records were both strengthened by infill walls, and the contribution of infill walls should be considered for better accuracy in the design process.     

The dynamic and thermodynamic processes dominating the reduction of global land monsoon precipitation driven by anthropogenic aerosols emission

Changes in monsoon precipitation have profound social and economic impacts as more than two-thirds of the world's population lives in monsoon regions. Observations show a significant reduction in global land monsoon precipitation during the second half of the 20 th century. Understanding the cause of this change, especially possible anthropogenic origins, is important.Here, we compare observed changes in global land monsoon precipitation during 1948–2005 with those simulated by 5 global climate models participating in the Coupled Model Inter-comparison Project-phase 5(CMIP5) under different external forcings.We show that the observed drying trend is consistent with the model simulated response to anthropogenic forcing and to anthropogenic aerosol forcing in particular. We apply the optimal fingerprinting method to quantify anthropogenic influences on precipitation and find that anthropogenic aerosols may have contributed to 102%(62–144% for the 5–95% confidence interval)of the observed decrease in global land monsoon precipitation. A moisture budget analysis indicates that the reduction in precipitation results from reduced vertical moisture advection in response to aerosol forcing. Since much of the monsoon regions,such as India and China, have been experiencing rapid developments with increasing aerosol emissions in the past decedes, our results imply a further reduction in monsoon precipitation in these regions in the future if effective mitigations to reduce aerosol emissions are not deployed. The observed decline of aerosol emission in China since 2006 helps to alleviate the reducing trend of monsoon precipiptaion.     

Amplitude-compensated Laplacian filtering of reverse time migration and its application

Reverse time migration is an advanced seismic migration imaging method. When the source wavefield and the receiver wavefield are cross-correlated, the cross-correlations of direct arrivals, backscattered waves and overturned waves will produce a lot of low-frequency noise, which will mask the final imaging results. Laplacian filtering, as a common method to suppress low-frequency noise, can adapt to any complex media, just adding a little computational cost. However, simple direct Laplacian filtering will destroy the characteristics of the useful signals. Therefore, the amplitude needs to be compensated before filtering when using the Laplacian filtering method. Zhang and Sun proposed an improved Laplacian filtering method and gave a simple calculation formula and explanation. This method can effectively suppress the low-frequency noise in reverse time migration while retaining the useful signal characteristics, but lacks detailed and strict mathematical derivation. Therefore, this paper gives a detailed and rigorous mathematical derivation of the amplitude-compensated Laplace filtering method from the point of view of amplitude-preserved filtering. The source wavelet is used instead of the source wavefield to compensate amplitude, just adding a little calculation cost. Finally, the amplitude-compensated Laplace filtering method is verified by two theoretical models and compared with the direct Laplacian filtering method.     

Magnetotelluric responses of three-dimensional conductive and magnetic anisotropic anomalies

A magnetotelluric finite-element modelling algorithm is developed, which is capable of handling three-dimensional conductive and magnetic anisotropic anomalies. Different from earlier three-dimensional magnetotelluric anisotropic modelling methods, the algorithm we presented has taken the magnetic anisotropy into consideration. The variational equations are produced by the Galerkin method and the governing equations are solved using a hexahedral vector edge finite-element method. The accuracy of this algorithm is firstly validated by comparing its solutions with the results of finite-difference method for a three-dimensional conductive arbitrary anisotropic model, and then validated by comparing with analytical solutions for a one-dimensional magnetic model. The responses of four kinds of models under different conditions are studied, and some conclusions are obtained. It shows that for materials with a high magnetic permeability, its influence on magnetotelluric responses cannot be ignored in some circumstances. Especially, if the magnetic susceptibility is exceptionally high, it may really distort the apparent resistivities of lower resistive anomalies. These conclusions are also beneficial for magnetotelluric survey.     

腹板摩擦式钢框架节点震后可更换性能的试验研究

主要针对梁腹板带有摩擦耗能螺栓的自复位钢框架节点结构进行抗震性能和可更换性能的试验研究,探讨该类节点在往复荷载作用下的滞回性能以及节点域的变形特征。在参数选型的基础上,对5组钢框架节点试件进行了低周反复荷载作用下的拟静力试验,其中:4组试件具有自复位能力,分析了各试件的承载力、刚度、耗能性能和滞回特性等性能。综合研究结果表明:所提出的拼接节点能够利用摩擦螺栓的滑移提高节点的耗能能力,有效减少梁和柱主体构件的损伤,同时预应力筋提供了结构的自复位能力。试验结果表明:在地震作用之后,通过更换腹板及摩擦螺栓可以使结构的承载能力和耗能性能与震前基本一致,从而实现结构功能的快速恢复。     

洪泽湖3种沉水植物附着细菌群落结构及多样性

沉水植物茎叶表面附着的藻、菌及其他物质,不仅影响沉水植物自身生长,而且影响水体物质循环过程,附着藻类的研究已经有不少报道,但附着细菌的报道相对较少.采用末端限制性片段长度多态性(T-RFLP)技术,研究洪泽湖典型沉水植物——菹草(Potamogeton crispus)、篦齿眼子菜(Potamogeton pectinatus)、金鱼藻(Ceratophyllum demersum)在生长旺盛期叶表面附着细菌的群落结构及多样性特征,并采用冗余分析法探讨环境因子对附着细菌丰度的影响.结果表明,(1)3种沉水植物附着细菌群落结构有明显的差异性.143 bp T-RF在菹草和篦齿眼子菜中的相对丰度平均达到了20%和11%,而在金鱼藻中的相对丰度小于1%;89 bp T-RF在金鱼藻中的相对丰度平均约为13%,而在菹草和篦齿眼子菜中相对丰度小于5%.94 bp T-RF在菹草样品中相对丰度超过15%,而在其他样品中未被检测出.(2)从多样性角度分析,3种沉水植物附着细菌多样性大小依次为篦齿眼子菜菹草金鱼藻.(3)部分限制性片段的丰度受环境因子的影响较大,如89、94、143和227 bp T-RFs.而如167 bp T-RFs在3种沉水植物中的相对丰度分布较为稳定,受上述环境因子的限制较小.根据细菌比对结果,洪泽湖附着细菌的优势菌群可能属于拟杆菌门(Bacteroides)、厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)3个门类.     

Potential petroleum sources and exploration directions around the Manjar Sag in the Tarim Basin

Since the discovery of the Tahe oilfield, it has been controversial on whether the main source rock is in the Cambrian or Middle-Upper Ordovician strata. In this paper, it is assumed that the crude oil from the Wells YM 2 and TD 2 was derived from the Middle-Upper Ordovician and Cambrian source rocks, respectively. We analyzed the biomarkers of the crude oil, asphalt-adsorbed hydrocarbon and saturated hydrocarbon in bitumen inclusions from the Lunnan and Hade areas in the North Uplift of the Tarim Basin. Results show that the ratios of tricyclic terpane C₂₁/C₂₃ in the crude oil, asphalt-adsorbed hydrocarbon and saturated hydrocarbon in bitumen inclusions are less than 1.0, indicating that they might be from Upper Ordovician source rocks; the ratios of C₂₈/(C₂₇+C₂₈+C₂₉) steranes in the saturated hydrocarbon from reservoir bitumen and bitumen inclusions are higher than 25, suggesting that they might come from the Cambrian source rocks, however, the ratios of C₂₈/(C₂₇+C₂₈+C₂₉) steranes in oil from the North Uplift are less than 25, suggesting that they might be sourced from the Upper Ordovician source rocks. These findings demonstrate that the sources of crude oil in the Tarim Basin are complicated. The chemical composition and carbon isotopes of Ordovician reservoired oil in the Tarim Basin indicated that the crude oil in the North Uplift (including the Tahe oilfield) and Tazhong Depression was within mixture areas of crude oil from the Wells YM 2 and TD 2 as the end members of the Cambrian and Middle-Upper Ordovician sourced oils, respectively. This observation suggests that the crude oil in the Ordovician strata is a mixture of oils from the Cambrian and Ordovician source rocks, with increasing contribution from the Cambrian source rocks from the southern slope of the North Uplift to northern slope of the Central Uplift of the Tarim Basin. Considering the lithology and sedimentary facies data, the spatial distribution of the Cambrian, Middle-Lower Ordovician and Upper Ordovician source rocks was reconstructed on the basis of seismic reflection characteristics, and high-quality source rocks were revealed to be mainly located in the slope belt of the basin and were longitudinally developed over the maximum flooding surface during the progressive-regressive cycle. Affected by the transformation of the tectonic framework in the basin, the overlays of source rocks in different regions are different and the distribution of oil and gas was determined by the initial basin sedimentary structure and later reformation process. The northern slope of the Central Uplift-Shuntuo-Gucheng areas would be a recent important target for oil and gas exploration, since they have been near the slope area for a long time.     

基于Labview平台LDAWYZ-1型水位仪软件系统设计与实现

介绍了LDAWYZ-1型水位仪软件系统的设计与实现过程,阐述了设计思路、各功能模块具体实现方法,并介绍了基于G语言的Labview编程平台及其在地震系统数据采集中的应用。     

软流圈物质运动对鄂尔多斯块体周缘断陷盆地运动特征的影响

研究软流圈物质运动及其对断陷盆地运动特征的影响,是揭示软流圈与岩石圈相互作用,认识华北克拉通破坏的深部动力学过程的基础.本文以鄂尔多斯块体周缘断陷盆地为研究对象,利用数值方法模拟了盆地底部软流圈物质的运动,进而分析了软流圈物质运动对周缘断陷盆地运动特征的影响.研究结果表明:(1)软流圈物质水平运动的区域流向为NWW-SEE向,流速基本一致,局部略有变化.随着深度增加,局部变化特征不再显著;(2)软流圈物质垂向运动存在区域性差异,其中鄂尔多斯体块体北部、西部以及北缘、西缘底部,物质以下沉流为主,尤其西缘下沉流更显著;块体中部、东部以及南缘、西南缘底部,以上升流为主;东缘底部,上升流与下沉流相间分布,以上升流为主.随着深度增加,上述区域性差异特征依然明显;(3)依据热物质的水平拖曳和垂向拉张作用对断陷盆地可能产生的影响,进一步推测,软流圈物质运动有利于北缘盆地的剪切走滑,东缘盆地的伸展拉张,南缘盆地的走滑兼拉张,西缘和西南缘盆地的走滑.     

An Elitist Multiobjective Tabu Search for Optimal Design of Groundwater Remediation Systems

This study presents a new multiobjective evolutionary algorithm (MOEA), the elitist multiobjective tabu search (EMOTS), and incorporates it with MODFLOW/MT3DMS to develop a groundwater simulation‐optimization (SO) framework based on modular design for optimal design of groundwater remediation systems using pump‐and‐treat (PAT) technique. The most notable improvement of EMOTS over the original multiple objective tabu search (MOTS) lies in the elitist strategy, selection strategy, and neighborhood move rule. The elitist strategy is to maintain all nondominated solutions within later search process for better converging to the true Pareto front. The elitism‐based selection operator is modified to choose two most remote solutions from current candidate list as seed solutions to increase the diversity of searching space. Moreover, neighborhood solutions are uniformly generated using the Latin hypercube sampling (LHS) in the bounded neighborhood space around each seed solution. To demonstrate the performance of the EMOTS, we consider a synthetic groundwater remediation example. Problem formulations consist of two objective functions with continuous decision variables of pumping rates while meeting water quality requirements. Especially, sensitivity analysis is evaluated through the synthetic case for determination of optimal combination of the heuristic parameters. Furthermore, the EMOTS is successfully applied to evaluate remediation options at the field site of the Massachusetts Military Reservation (MMR) in Cape Cod, Massachusetts. With both the hypothetical and the large‐scale field remediation sites, the EMOTS‐based SO framework is demonstrated to outperform the original MOTS in achieving the performance metrics of optimality and diversity of nondominated frontiers with desirable stability and robustness.